Muzzle choke



- Feb. 3, 1970v `A SHBOOK Em. 3,492,750

MUZZLE CHOKE Filed Nov. 15, 1967 2 sheets-sheet 2 Alvor/ver' 3,492,750MUZZLE CIIOKE Clifford Logan Ashbrook, 5027 Cheena 77035, and WilsonGordon Wing, 33 E. Rivercrest 77042, both of Houston, Tex.

Filed Nov. 15, 1967, Ser. No. 683,200 Int. Cl. F41f 17/12 U.S. Cl. 42-7911 Claims ABSTRACT F THE DISCLOSURE A shot diverter for use with ashotgun and in which the diverter includes upper and lower walls andside walls. The upper and lower walls converge from rear to front.Likewise the side walls converge from rear to front but at an angle withrespect to each ,other which is different from the angle which the upperand lower walls converge towards each other. A plurality of Shotdiverting ridges are integrally disposed on the walls and oriented in agenerally rear to front manner.

This application constitutes a continuation-in-part of our priorco-pending application tiled Aug. 14, 1967, and bearing Ser. No.660,446.

Background ,of the invention The present invention relates to a muzzledevice for use with firearms and, more particularly, firearms of ashotgun variety.

It is desirable in a variety of firearm applications to produce ashotgun shot pattern of elliptical form with the major axis thereofresiding in the horizontal plane and the minor axis in the verticalplane. Such a shot distribution is found to have considerable value innumerous and varied applications such as game hunting, guerilla warfare,and civil riot control. The primary advantage of such a shotdistribution pattern is obvious, that being a much higher probability ofstriking the intended target with the missiles of the firearm.

Although numerous attachments, chokes, and other forms of shot-shapingdevices have been designed heretofore for utilization with the muzzle ofa shotgun, none have adequately and reliably solved the problem ofpredetermined shot distribution. Such devices are generally bulky,difficult and/or dangerous to use, and do not provide results inaccorance with the intended or desired purpose. The problem has beenengaged from a number of viewpoints by the prior art including theutilization of gas relieving apertures in the muzzle device for ventingexplosion gases quickly to atmosphere in a manner similar to the'present invention, laterally extending slots in the wall of the shotgunbore or in the walls of an attachment thereto for permitting horizontalexpansion of the shot pattern upon tiring (United States Patent No.3,226,871), and a wide variety of conventional and rather unconventionalchoke designs. Although certain of these devices have, in fact, tendedto achieve some predetermined pattern of shot, the pattern has not beenreasonably predictable, nor has the success in achieving such a patternbeen consistent over va plurality of firings. The devices themselveshave, at times, proven dangerous, due to their tendency to fractureafter a number of repeated firings. It is these shortcomings anddeficiencies which has occasioned and motivated the present invention.

This invention constitutes a first recognition of the sophisticatedrequirements necessary for achieving controlled distribution of themissiles of a shotgun shell. There is described herein a cage anddiverter device working cooperatively to both vent specific types ofgases from the bore of a shotgun, while at the same time permittingStates Patent ICC the conventional choking action in conjunction with.other structures for producing a predetermined distribution of shotupon a remote target. The invention, therefore, not .only obviates theprimary obstacle to which prior art devices have been directed but, inaddition, provides a structure which is both reliable and safe; andwhich is easy to handle, simple in operation, eicient in use, andrelatively inexpensive to manufacture. These, and numerous otherfeatures and advantages of the invention, shall become more readilyapparent to the reader upon examination of the following detaileddescription, claims, and drawings, wherein like numerals denote likeparts in the several views, and wherein:

FIGURE l shows in perspective a preferred form of the invention.

FIGURE 2 shows the diverter and cage sections of FIGURE l removed fromeach other and viewed obliquely from the rear thereof.

FIGURE 3a illustrates schematically a rst position of a shotgun shell asit traverses the bore.

FIGURE 3b illustrates a second position of a shotgun shell as ittraverses the bore toward the cage aperture showing also the forms ofgasses acting upon the wad of the shell.

FIGURE 3c shows a third position of the shell as it traverses the boreand after the wad has substantially passed the cage aperture of thesection of the subject invention.

FIGURE 4a illustrates a front view or the exit end of the invention ofFIGURE 1.

FIGURE 4b illustrates a sectional view of the diverter of FIGURE 2 alongthe plane 4 4 thereof.

FIGURE 5 is a vertical sectional view along the plane 5 5 of FIGURE 4a.

FIGURE 6 is a horizontal sectional view along the plane 6 6 of FIGURE4a.

With reference now to FIGURES l and 2 of the drawing, there is shown inpreferred form, but for exemplary purposes, the diverter 5 and cagesections 3 of the invention. The diverter is characterized by anelongated cylindrical like body having a right side wall 11 and leftside wall 13 opposite one another. Although the diverter is of generallyfrusto-conical configuration, its upper and lower surfaces are machinedto define the upper wall 7 and lower wall 9. Machining of these wallstends to reduce the `overall weight of the diverter section thus makingit easier to handle. Machining such surfaces also tends to maintainsubstantially constant wall thickness throughout the longitudinal lengthof the diverter, thus reducing the tendency towards creation ofdifferential metal pressures and fatigue created by elevatedtemperatures. The rearward portion of the diverter tube 5 ischaracterized by the threaded end connection 27 which has a reduceddiametrical dimension by comparison to the rearward end of the right andleft walls 11 and 13 respectively. The magnitude of the difference indiameter is illustrated by the diverter flange wall 37 which mates inintimate contact with the front wall 39 of the cage member 3.

Cage member 3 is of generally cylindrical configuration, having anelongated central bore 40 axially aligned with the diverter bore 41described hereinafter. The elongated central bore 4t) is characterizedby the internal threaded connection 31, 32 at the exit and entry endsthereof respectively. The threaded connection 31 at the exit end of thecage is of such predetermined internal diameter as to cooperativelyreceive and engage a threaded connection 27 of the diverter tube S. Thecage member 3 further includes a plurality of aperturescircumferentially disposed about the surface thereof, the aperturesbeing defined by the longitudinal aperture walls 15, 17 (see FIGURE 1)and the rearward and forward lateral aperture walls 19, 21 respectively.The four walls intersect to form a plurality of the apertures such asthree as is shown in the illustration. The longitudinal aperture walls15, 17 are of planar type surface except at the forward corners thereof,where a fillet or corner curved surface 23 is provided so as to form asmooth intersection with the forward lateral walls 21. These fillets orgrooves on the comers of the cage vertical and horizontal walls serve toenhance turbulence of escaping gases upon the passage of a projectilethrough the cage member. Such turbulence lowers the pitch of audio-typewaves, thus causing a very substantial reduction in the overal noiselevel when the weapon is fired.

As is best shown in FIGURES 3a through 3c, the diverter and cage of theinvention are ordinarily affixed to the end of a muzzle, such as that ofa shotgun. In FIGURE 3a there is shown the position of a typical wad 24of a shotgun shell as it approaches the apertures of the cage member 3subsequent to firing. Prior to the time at which the shell reaches theaperture, there of course can be no escape of any of the gases behindthe shell. Upon intersection of the wad with the aperture, there iscreated an immediate release of the gas pressure behind the wad. It hasbeen found in accordance with this invention that the gases followingthe wad as it passes through the cage and diverter may be generallyconsidered to be either of the hard gas variety or the soft gas variety.The hard gas is generally -of a laminar fluid species while the soft gasis more turbulent in nature. In accordance with the invention, it isfurther known that as the rear wall of the wad opens from the rearlateral wall 19 of the aperture, the gases following the wad are emittedinto the aperture at an initial expanding angle which varies fromdegrees, 8 minutes to 6 degrees, 0 minutes. It will, of course, berecognized that these gases 49 are primarily of a soft gas nature and atthe time of their initial escape tend to increase the recoil reaction onthe muzzle. AS these gases expand forwardly, however, they come intocontact with the forward lateral aperture wall 21 and react thereon,thus tending to reduce the recoil reaction of the weapon. In order tomaximize the effect of the impinging gases upon this wall, the wallitself is constructed at a six degree (6) angle (or less) with respectto a plane running perpendicular to the longitudinal axis of thediverter tube. The diverter tube rear wall 29 is similarly sloped at anangle alpha, or in the maximum case, six degrees (6), since this wallconstitutes an extension of the forward lateral wall 21 of the aperturewhen the diverter tube is threaded into the cage member. It will thus beseen that the angle alpha is so calculated as to create a surface whichis perpendicularly oriented with respect to the impact points of thesoft gas 49. The forward lateral wall 21 of the aperture is likewise sooriented. The reason for the angular deflection of gases as explainedabove lies in the creation of the hard gas characteristic or laminar gaslayers 43 discovered as an incident to this invention. The hard gas 43proceeds behind the shell wad 24 and is of generally conical shape. Theconically shaped hard gas or concentrated gas molecules act as adeecting cone for gases following therebehind, thus causing such gasesto be defiected outwardly at the angle disclosed above. These followinggasses create a pulsing reaction on the forward lateral aperture wall21. This pulsing action is found to account for a signicant increase, ofup to five percent in the shell velocity. An advantage of this is theimproved pattern predictability which results. A further advantage ofthe specific aperture structure of the cage member 3 resides in thesubstantial absence of any flash either at the exit end of the divertertube S or at H the apertures of the cage member 3, upon firing. This maybe explained by the stacking effect of the heated gases (FIGURE 3c) inthe central bore of the cage member as the shell passes therethrough andby the calculated deflection of gases back towards the apertures.

This reflection of the soft gas flow tends to increase the gastemperature within the cage, thus elevating the pressure therein. As aconsequence, the gases are ignited well within the bore of the cagemember, rather than outside it, thus substantially eliminating theobservance of any illumination upon firing of the weapon.

Reference may now be made to FIGURES 4a and 4b in conjunction withFIGURES 1 and 2. Here, there is shown the shot diverting ridges 51 forcreating the predetermined pattern of shot upon a target all inaccordance with the teachings herein. Although the diverter bore 41 isshown in FIGURE 1 to include three diverter ridges on each the upper andlower surface, it will be recognized that any number of diverter ridgescan be utilized in the practice of this invention. The function of thesemi-circular areas which characterize the diverter tube and which aredefined by the diverter ridges 51 is to guide in a predetermined mannerthe shot pellets of a shell as they traverse the bore. Thus, in a borefor a #4 buckshot such as is illustrated in FIGURE 4a, there wouldreside in front of the wad Ysix (6) spherical pellets disposed inaccordance with the cross-sectional pattern of the bore, there being oneadditional pellet behind the six and at the center thereof. Since thefunction of the bore, regardless of the number of pellets to becontained therein, is to reshape the shot distribution in alongitudinally expanded and vertically suppressed manner, the internalslopes of the bore are designed to accomplish this object. Thus, theupper and lower ridges 51(a) [FIGURE 4b] slope from the diverter rearwall 29 towards the central axis as they approach the front or exit endof the diverter tube. As shown in FIGURE 5, the slope may preferablyrange between l.5 to 3.5 degrees with respect to the horizontal. Whenviewed in the horizontal plane (see FIGURE 6), the bore likewiseconverges from the rear end to the front end so as to create the desiredlongitudinally elongated shot pattern. It is thus seen that the diverterin effect creates a volumetric change per unit of length or as mightotherwise be described, volumetrically diminishes and expands the shotper unit of length or advance in the bore. It should further be pointedout that the interior surface of the diverter, or, more specifically,the bore thereof, need not be perfectly smooth as is the commonpractice. It has been learned in accordance with this invention that thesurface may be intentionally roughened so as to disturb the shot as ittraverses the bore. This tends to make the shot more amenable to shapingby reason of its constant bouncing and movement as it travels down thebore. In this manner substantially improved shot distribution patternsare achieved. A surface roughness of fifty (50) micro-inches to onehundred twenty-five microinches is recommended for this purpose. As bestshown in FIGURE 4b and FIGURE 2, the central-upper and lower shotdiverting ridges are more pronounced nearer the exit end of the divertertube and, in fact, the ridges gradually merge into the upper and lowersurface of the tube as they approach the diveter rear wall 29. Thus, asshown in FIGURE 2, these two diverter ridges therefore are notobservable.

In operation, when a shell is fired, the spherical pellets contact thesloping sides 53, 55, 53a, 55a, and are vertically concentrated in aninward direction towards the horizontal plane in which the central axislies. At the same time, the shot is compressed outwardly when viewed inthe horizontal plane (FIGURE 6), this despite the fact that the sides59, 57 converge from rear to front. There can, for example, be produceda uniformly distributed pattern of shot within a two (2) foot high byfifteen (15) foot wide rectangle at thirty (30) yards, compared to aconventional circular pattern of two 2) feet or less. The shell wad,even when of the relatively dense and heavy military type, passesthrough the reduced mouth area without damaging the shotgun due to thesubstantial and effective gas pressure relief provided by the aperturein the cage member 3.

It will be recognized that numerous and various modifications of thepresent invention may be made without departing from the spirit andscope thereof. For example, as previously mentioned, any number of shotdiverting ridges could be utilized in accordance with an intendedpattern. Similarly it will be recognized that, contrary to the teachingshereinabove, the upper and lower walls could be made to converge at anangular rate to the longitudinal axis which is less than that at whichthe side Walls converge with respect thereto. There would thus beobtained a vertically expanded, horizontally reduced pattern of shotwhen compared to the conventional shot distribution. It is consideredfeasible even to provide an incremental slot either in the side walls orthe upper and lower walls of the diverter tube adjacent the diverterbore at theV front end thereof. Such a slot could be so calculated so asto expand the pattern either verticallyor horizontally in accordancewith the desired result. Still other modifications within the spirit ofthe invention and the scope of the appended claims may occur to thoseskilled in the art,

Therefore, what is claimed and desired to be secured by United StatesLetters Patent is: t

1. A shot diverter for use with a shotgun for producing a verticallyreduced-horizontally expanded pattern of shot distribution on a remotetarget comprising:

an elongate tubular body having an entry end, an exit end, and animaginary longitudinal axis extending therebetween, the interior of saidtubular body being defined by upper and lower wall means and side wallmeans, said upper and lower wall means being arranged to graduallyconverge from the entry end to the exit end, said side wall means beingsimilarly disposed to gradually converge from the entry end to the exitend,

the angular rate of convergence of said side walls being smaller thansaid upper and lower walls so that the pattern of shot emerging from theexit end is concentrated more by the upper and lower walls than by theside walls to thereby produce the vertically reduced-horizontallyexpanded pattern of shot distribution, and

ridge means disposed on at least one of said wall means for influencingthe direction of shot movement as it tranverses the body.

2. The shot diverter of claim 1 wherein said ridge means are disposed onthe upper and lower wall means in diverging manner with respect to theimaginary longitudinal axis when viewed from the entry to the exit endof the body so as to further enhance selective movement of certain ofthe shot into a horizontally expanded pattern.

3. The shot diverter of claim 2 wherein said ridge means are disposed onsaid side wall means in converging manner from entry to exit end so asto enhance the direction of movement of certain of the shot into avertically reduced pattern of distribution even though the shot may notbe fully in contact with the upper or lower vWall means.

4. The shot diverter of claim 3 wherein said ridge means are mostprounced at the exit end and become proportionately less pronounced perunit of length towards the entry end, thereby gradually slopingdownwardly from the exit to the entry end so as to merge into thesurface of said wall means proximate the entry end, and therebyproviding for gradual but positive alignment of selective shot pelletsinto predetermined directions.

5. The shot diverter of claim 2 wherein said ridge means are mostpronounced at the exit end and become less pronounced per unit of lengthtowards the entry end,

6 thereby gradually sloping downwardly from the exit end to the entryend so as to merge into the surface of said wall means proximate theentry end, and thereby providing for gradual but positive alignment ofselective shot pellets into predetermined directions.

6. The shot diverter of claim 1 wherein said ridge means are disposed onsaid side wall means in converging manner from entry to exit end so asto enchance the direction of movement of certain of the shot into avertically reduced pattern of distribution even though the shot may notbe fully in contact with the upper or lower wall means.

7. The shot diverter of claim 6 wherein said ridge means are mostpronounced at the exit end and become proportionately less pronouncedper unit of length towards the entry end, thereby gradually slopingdownwardly from the exit end to the entry end so as to merge into thesurface of said wall means proximate the entry end, and therebyproviding for gradual but positive alignment of selective shot pelletsinto predetermined directions.

8. The shot diverter of claim 1 wherein said ridge means are mostpronounced at the exit end and become proportionately less pronouncedper unit of length towards the entry end, thereby gradually slopingdownwardly from the exit to the entry end so as to merge into thesurface of said wall means proximate the entry end, and therebyproviding for gradual but positive alignment of selective shot pelletsinto predetermined directions.

9. The diverter of claim 1 wherein said elongate tubular body furtherincludes, adjacent the entry end thereof, means for suppressing fiashand noise upon firing of the gun.

10. The diverter of claim 1 wherein said means for suppressing noiseincludes a plurality of apertures defined by longitudinal and lateralwalls, the intersection of said longitudinal and lateral walls beingcharacterized by fillet means for creating areas of turbulent gas flow,thereby reducing the pitch of audio waves omitted through saidapertures.

11. The diverter of claim 1 wherein said lateral walls extend around amajor portion of the perimeter of said tubular body and aresubstantially equidistant from each other and,

each of said longitudinal walls are of substantially the same length assaid lateral walls to thereby provide a plurality of equidistantlyspaced apertures which exposes a major portion of the tube interior tothe atmosphere so as to permit the total reflection of soft gases backover the apertures in covering relation thereto as a shell wad passesdown the tubular body, thereby elevating the pressure of hard gases inthe tube in order to enhance ignition in the bore and thus eliminatingvisible flash.

References Cited UNITED STATES PATENTS 587,801 8/ 1897 DurnfOrd 42-791,636,357 7/1927 Cutts t. 89-14 1,773,260 8/1930 Cutts 42--79 2,658,29811/ 1953 Oberfell 42-79 3,226,871 1/ 1966 Sargeant et al. 42-792,602,255 7/ 1952 Cutts 42-79 SAMUAL W. ENGLE, Primary Examiner U.S. Cl.X.R. 89--14

